Chapter 11. Ethernet Module
11-25
Programming Model
11.5.15 Transmit Control Register (X_CNTRL)
The X_CNTRL register, Figure 11-18, controls the operational mode of the transmit block
Table 11-22. describes the X_CNTRL fields.
Table 11-21. MAX_FRM_LEN Field Descriptions
Bits
Name
Description
31
BRDCAST
Broadcast address received. Set if the current receive frame contained a destination
address of all ones (the broadcast address). Cleared if the current receive frame does not
correspond to a broadcast address.
30
MULTCAST Multicast address received. Set if the current receive frame contained a multi-cast
destination address (the least significant bit of the DA was set). Cleared if the current
receive frame does not correspond to a multi-cast address.
29–24
HASH
Current hash value. Corresponds to the hash value of the current receive frame’s
destination address. The hash value is a 6-bit field extracted from the least significant
portion of the CRC register.
23–11
—
Reserved, should be cleared.
10–0
MAX_FL
Maximum frame length. Length is measured starting at DA and includes the CRC at the
end of the frame. Transmit frames longer than MAX_FL cause the BABT interrupt to occur.
Receive frames longer than MAX_FL cause the BABR interrupt to occur and set the LG bit
in the end-of-frame buffer descriptor. Frames exceeding the MAX_FL are not truncated.
Transmit frames are never truncated, but receive frames are truncated at 2k-1 bytes. The
MAX_FL field resets to 1518 decimal and can be programmed either smaller or larger (up
to 2k-1). The recommended default value to be programmed by the user is 1518 or 1522 (if
VLAN Tags are supported).
31
16
Field
—
Reset
0000_0000_0000_0000
R/W
Read/Write
15
3
2
1
0
Field
—
FDEN HBC GTS
Reset
0000_0000_0000_0000
R/W
Read/Write
Addr
MBAR + 0x984
Figure 11-18. Transmit Control Register (X_CNTRL)
Table 11-22. X_CNTRL Field Descriptions
Bits
Name
Description
31–3
—
Reserved, should be cleared.
2
FDEN
Full duplex enable. If set, frames are transmitted independent of carrier sense and collision
inputs. This bit should only be modified when ETHER_EN is deasserted.
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...